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UNrrnn STATES,

PATENT RENE BOHN, OF MANNHEIM, ASSIGNOR TO THE BADISCHE ANlLlN AND SODA FABRIK, OF LUDWIGSHAFEN, GERMANY.

BLACK DYE.

SPECIFICATION forming part of Letters Patent No. 545,337, dated August 27, 1895.

Application filed October 9. 1894. Serial No. 525,865. (Specimens) Patented in England June 5, 1893, No. 10,996, and in France April 7,1894,No. 237,616.

To all whom it may concern:

Be it known that I, RENE BOHN, doctor of philosophy, a citizen of the Swiss Republic,

residing at Mannheim, in the Grand Duchy of Baden and Empire of Germany, have invented new and useful Improvements in the Manufacture of New Black Coloring-Matter, (for which patents have been obtained in England, No. 10,996, dated June 5, 1893, and in France, No. 237,610, dated April 7, 1894,) of which the following is a specification.

It is well known that on nitrating naphthalene in such a way that two nitro groups enter the molecule a mixture containing two isomeric dinitro-napthalenes is obtained namely, the so-called 1.4: and 1.1 dinitronaphthalencs.

My present invention relates to the production of new black coloring-matters which are obtained by the treatment of the said dinitronaphthalenes, either singly or in admixture one with the other, under suitable conditions, with sodium sulfid, as is hereinafter more particularly set forth. Already in the early years of thecoal-tar-color in dustry unsuccessful attempts were made to produce useful dyes from the mixture of these nitro compounds, although such had been obtained from nitro-benzene. Thus in 1861 Troost experimented on the action of alkaline-reducing agents on the said dinitro-naphthalenes with a view to the foundation of a practical manufacture; but neither he nor other chemists- Roussin, Carey-Lea, Kopp, and others-who made experiments with a similar object attained any useful result, and all experiments of this kind were abandoned, and for over thirty years nothing more has been published with reference to this problem. In the meantime one constituent of the above-mentioned mixture-namely, the so-called 1.4: or alphadinitro-naphthalene has come into use in large quantities in the manufacture of naphtha-zarine, of 1.4 naphthalenendiamin, and of other bodies. No useful application, however, has been discovered for the 1.1 dinitro compound, and this consequently constitutes a valueless and irksome by-product in the above manufactures Now I have invented processes for the production of very valuable new black coloring-matters from this hitherto useless icy-product. The said coloring-inatters cannot be used in dyeing in the usual way; but if they be applied to cotton, linen, jute, or the like by using a strongly alkaline dye-bath or printing-mixture, with or without the addition of a reducing agentsuch as grape-sugarthen fine black shades are obtained, resisting the action of acids, alkalies, andlight. Two different products possessing this generic property are obtained, according to the conditions of concentration, temperature, and proportions of reagents used. Under ordinary, conditions a mixture of these products is usually obtained. These need not be separated from one another in practical working, as the mixture can be directly used for dyeing or printing. The two products differ mainly with reference to their solubility in soda solution, one being soluble in that reagent, the other insoluble or nearly so.

In the present application I do not intend to claim my new black coloring-matters generically, nor 'the specific coloring-matter, which-is insoluble in soda solution, for these are covered by a separate application filed October 9, 1894, No. 525,364; but what Iwish to protect by this application is the specific coloring-matter, soluble in soda solution, hereinafter described.

The following example will serve to illustrate the manner in which my invention can best be carried into practical effect and the new dye obtained. The parts are by weight.

Example: Production of the coloring-mattea" soluble in hot soda s0Zut'ion.-Mix together about fifty parts of the 1.1 dinitronaphthalene, about one hundred and sixty parts of water, and about one hundred and sixty-five parts of sodium sulfid, (Na S+9Aq.) Stir the mixture cold for about five hours or until no unchanged dinitronaphthalene remains; then dilute with about five hundred (500) parts of water, filter, and acidify cold with about three hundred (300) parts of acetic acid, filter, and wash. The product so obtained is in the main soluble in hot soda solution, but usually contains some dye insoluble therein, from which it can readily be purified, if desired. For this purpose dissolve the product in about five thousand (5,000) parts of hot soda solution, [containing ten per cent. (10%) Na GO filter, and precipitate with hydrochloric acid. filter, and wash, and preserve as paste. This dye can be used in the same way as the coloring-matter, insoluble in soda solution, with or without the addition of grape-sugar, and mixtures of the two dyes, however obtained, can be used in the manner described without separation one from another. 7

My new black coloring-matter is characterized by its peculiar relation to the fiber, in that it cannot practically be used in dyeing in the usual way,but only in astrongly-alkaline dye-bath containing up to about twentyfive per cent. Na OO The new black coloring-matter (soluble in soda solution) so obtained occurs as a greenblack paste, or, when dry, as a blue-black powder with metallic luster. On boiling with soda solution it yields a violet solution. In concentrated sulfuric acid it dissolves and the solution is dirty green in color, turning blue on heating and then dirt-y red. It is practically insoluble in alcohol.

Although in the above example I have de- SCIibQCltllG use of 1.1 dinitro-naphthalene, still in practically manufacturing it is not necessary to isolate the dinitro body, but a mixture thereof containing the aforesaid 1A dinitro-naphthalene can be used. In this case the properties of the product obtained are somewhat affected by the presence of the similar compounds obtained from the 1.4: compound, but the product obtained can be practically applied in the sameway.

Now, what I claim is- The specific black coloring matter which can be obtained by treating dinitro-naphthalens with sodium sultid and subsequentlywith acetic acid and can be applied to vegetable fiber by the aid of a strongly alkaline dye bath and which is soluble in soda solution giving a violet solution, soluble in concentrated sulfuric acid giving adirty green solution turning blue and dirty red on heating,

substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

RENE BOHN.

Witnesses:

ERNEST F. EHRHARDT, ADOLPH REUTLINGER. 

